Ordering in channel inclusion compounds of TANO with linear-chain compounds. I. High- and low-temperature structures of TANO–<i>n</i>-heptane

Bars-Combe, M. Le; Lajzérowicz, J.

doi:10.1107/s0108768187097684

Cited by 16 publications

(5 citation statements)

References 11 publications

(17 reference statements)

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“…This value is in good agreement with that obtained from previous differential scanning calorimetry measurements: H t = 2.0 ± 0.2 cal g −1 . The relative high value compared to the enthalpy of fusion ( H t / H f = 13%) was explained by the participation of the tano molecules in the phase transition mechanism (reconstructive first-order transition) [1].…”

Section: Effect Of Hydrostatic Pressure On the Transition Temperaturementioning

confidence: 99%

“…At room temperature, all the tano inclusion compounds are monoclinic (C2/c, Z = 24) with similar crystallographic parameters (a = 36 Å, b = 5.95 Å, c = 35.5 Å, β = 120 • ), revealing a similar organization of the whole tano matrix. There are four channels parallel to b in a cell, 18 Å apart and 5 Å in diameter (see figure and description of the structure in [1]).…”

Section: Introductionmentioning

confidence: 99%

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Pressure dependence of the dynamics of an organic inclusion compound investigated by incoherent quasielastic neutron scattering

Combet¹,

Morelon

Ferrand

et al. 1997

J. Phys.: Condens. Matter

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The nitroxide (referred to as tano) forms channel inclusion compounds with linear hydrocarbons. At room temperature, both tano and chain molecules are dynamically disordered. When the temperature is decreased, one phase transition is observed. The pressure dependence of the temperature of transition and the evolution of the individual motions have been studied by incoherent quasielastic neutron scattering in the case of a tano - octane system. The transition temperature increases with the pressure with a slope . The transition mechanism is connected to the lock-in of both tano (interconversion) and chain (reorientation) molecules, as a result of strong correlations between host and guest substructures. A residual disorder persists in the low-temperature phase confirming that all the tano molecules are not dynamically equivalent.

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Section: Effect Of Hydrostatic Pressure On the Transition Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pressure dependence of the dynamics of an organic inclusion compound investigated by incoherent quasielastic neutron scattering

Combet¹,

Morelon

Ferrand

et al. 1997

J. Phys.: Condens. Matter

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“…Typically, for tano-heptane at T = 233 K, a = 36´0°A, b = 5´95°A, c = 35´5°A, b = 120 Â . The guest molecules are enclosed end-to-end into parallel channels, having a diameter of 5 A Ê and being 18 A Ê apart [1,2]. X-ray rotation photographs show homogeneous di use layers perpendicular to the direction of the b axis, i.e., the long axis of channels.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of bromohexadecane and bromodecane chains included in an incoherent quasielastic neutron scattering study an organic matrix

Bée¹,

Combet²,

Djurado³

1997

Molecular Physics

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The nitroxide C 9 H 16 NO 2 (tano) forms channel inclusion compounds with a large range of linear chains or slightly branched molecules. All of them present disorder phenomena of the guest chains in the channels of the structure, but also of the host matrix molecules from one chiral form to the other. The evolution of this disorder as a function of the temperature is accompanied by one or two phase transitions above 100 K. The incoherent quasielastic neutron scattering (IQNS) technique was used to study the motion of the tano molecules for the tano/1-bromohexadecane and the tano/1-bromodecane systems in their low, intermediate and high temperature phases. The experiments were carried out on a polycrystalline sample at the Institut Laue± Langevin in Grenoble using the time-focusing time-of-¯ight spectrometer IN6 with a temperature ranging from 103 K to 300 K. The motion of the guest chains also was shown. The results are examined in terms of the general model proposed in an earlier IQNS study of other tano/alkane compounds with shorter included chains and the original features associated with the chain length are discussed. IntroductionThe nitroxide radical 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl, C 9 H 16 NO 2 , (® gure 1), referred to as tano, forms stable crystalline inclusion compounds with linear n-alkanes C n H 2n+ 2 for n ranging from 7 to 44 at least [1± 5]. These compounds show analogies with urea or thiourea inclusion compounds [6]. However, the percentage of alkane to tano is only 5% by weight.At room temperature, X-ray analyses show that all the alkane inclusion compounds are isomorphous: space group C2/c, Z = 4 and their crystallographic parameters di er by less than 1%. Typically, for tano-heptane at T = 233 K, a = 36´0°A, b = 5´95°A, c = 35´5°A, b = 120 Â . The guest molecules are enclosed end-to-end into parallel channels, having a diameter of 5 A Ê and being 18 A Ê apart [1, 2]. X-ray rotation photographs show homogeneous di use layers perpendicular to the direction of the b axis, i.e., the long axis of channels. Their spacing is strictly related to repetition length L of the alkane chains along the channels. There is an incommensurability between L and b. The thickness of the di use planes supports the good periodicity of the

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“…In the case of TANO-nheptane (m = 2, n -1 ), of which HT and LT structures were described in paper I [Le Bars-Combe & Lajzerowicz (1987). Acta Cryst.…”

Section: A(lt)=a(ht)/2 B(lt)=mb(ht)=nl (M and N Integers)mentioning

confidence: 99%

“…In paper I (Le Bars-Combe & Lajzerowicz, 1987), we presented the main features of these compounds and gave the structural results for high-(233 K) and low-(173K) temperature phases of TANO-nheptane.…”

Section: Introductionmentioning

confidence: 99%

Ordering in channel inclusion compounds of TANO with linear-chain compounds. II. Phase transitions of TANO–n-alkanes

Bars-Combe¹,

Lajzérowicz²

1987

Acta Crystallogr Sect B

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Numerous phase transitions of channel inclusion compounds of the nitroxide radical 2,2,6,6-tetramethyl-4-oxopiperidine 1-oxide or TANO (C9HI6NO2) with n-alkanes (CnH2n+2) were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (one transition if 7-< n-< 11, two transitions if 12-< n -< 19). Temperatures and enthalpies of transition and fusion are given. In the hightemperature phase (HT), complete disorder of the included alkanes is found in the channels parallel to the b axis: homogeneous diffuse layers perpendicular to b are seen on X-ray photographs, whose spacing is strictly related to the alkane length 1 (incommensurate with the b parameter). For all the compounds studied, lock-in transitions exist. In the lowtemperature phase (LT), diffuse layers disappear and new Bragg reflections appear. The new lattice is a(LT)=a(HT)/2, b(LT)=mb(HT)=nl (m and n integers).The observations suggest helical arrangements of TANO molecules. In the case of TANO-nheptane (m = 2, n -1 ), of which HT and LT structures were described in paper I [Le Bars-Combe & Lajzerowicz (1987). Acta Cryst. B43, 386-393], the evolution of the cell parameters and the intensities of reflections are presented as a function of temperature. For n-12, intermediary complex phases exist.

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Ordering in channel inclusion compounds of TANO with linear-chain compounds. I. High- and low-temperature structures of TANO–n-heptane

Abstract: The nitroxide radical 2,2,6,6-tetramethyl-4-oxopiperidine 1-oxide or TANO (C9H16NO2) forms channel inclusion compounds with numerous linear chain compounds. In the high-temperature phase, included chains are disordered in the channels (orientation and l~osition).

Cited by 16 publications

References 11 publications

Pressure dependence of the dynamics of an organic inclusion compound investigated by incoherent quasielastic neutron scattering

Pressure dependence of the dynamics of an organic inclusion compound investigated by incoherent quasielastic neutron scattering

Dynamics of bromohexadecane and bromodecane chains included in an incoherent quasielastic neutron scattering study an organic matrix

Ordering in channel inclusion compounds of TANO with linear-chain compounds. II. Phase transitions of TANO–n-alkanes

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